1. Field of the Invention
The present invention relates to a contactless rotation angle sensor serving to detect the rotation angle of various apparatus or the rotation amount of a rotating body to be detected moving with a gearshift operation of an automatic transmission.
2. Description of the Related Art
There has been known a contactless rotation angle sensor described in Japanese Patent Application Laid-Open No. 2003-269992 as a conventional one. The structure of the contactless rotation angle sensor is such that the inside of a case is separated into two spaces by a partition to store a rotation mechanism section in the one space and an electric circuit section in the other. The one space of the case storing the electric circuit section is closed by a second lid and a space between the case and the second lid is sealed with a small amount of resin and an O ring.
For this reason, the electric circuit section stored in the other space of the case can be sealed by the second lid and the O ring.
Such a structure, however, has a problem in that water is prone to be accumulated in the one space of the case storing the rotation mechanism section and the accumulated water evaporates to expose the electric circuit section to moisture, degrading durability and a detecting accuracy. The structure has another problem in that it requires sealing resin and an O ring and cannot be applied to such a structure that a detected rotating body passes through the center of the case.
Japanese Patent Application Laid-Open No. 2003-269992
There have be solved such problems that water is prone to be accumulated in the one space of the case storing the rotation mechanism section to degrade durability and a detecting accuracy, and the structure requires sealing resin and an O ring and cannot be applied to such a structure that a rotating body to be detected passes through the center.